Process for purification of crude polyether polyols

Abstract

A process for purifying crude polyether polyols which are prepared by anionic polymerization of alkylene oxides in the presence of basic catalysts. The polyols are mixed with water and ortho-phosphoric acid in certain quantity ratios, an adsorption agent is incorporated in the reaction mixture, the mixture is filtered and the water is removed from the polyether polyol by distillation.

The embodiments of the invention in which an exclusive privilege or property is claimed are defined as follows: 
     
       1. A process for the purification of crude polyether polyols prepared by anionic polymerization of alkylene oxides in the presence of basic catalysts and subsequent neutralization of the catalysts with mineral acid wherein the (a) crude polyether polyol is mixed with 0.2 to 1.5 parts by weight of water per 100 parts by weight of crude polyether polyol, and 0.3 to 1.1 moles of ortho-phosphoric acid per mole of alkaline catalyst,   (b) 0.05 to 0.5 parts by weight of an adsorption agent per 100 parts by weight of crude polyether polyol are subsequently incorporated in the reaction mixture,   (c) the resultant salts and solid additives are separated, and   (d) the water is removed from the polyether polyol.   
     
     
       2. The process of claim 1 wherein the crude polyether polyol is mixed with water and phosphoric acid at temperatures of 50° C. to 140° C. and optionally under increased pressure. 
     
     
       3. The process of claim 1 wherein the reaction mixture of polyether polyol, water and phosphoric acid is agitated at temperatures of 50° C. to 140° C. for 0.1 to 4 hours and the adsorption agent is subsequently incorporated in the reaction mixture. 
     
     
       4. The process of claim 1 wherein magnesium silicate is used as adsorption agent. 
     
     
       5. The process of claim 1 wherein the resultant salts and incorporated solid additives are separated by filtration. 
     
     
       6. The process of claim 1 wherein the filtration is carried out in the presence of a filtering aid. 
     
     
       7. The process of claim 1 wherein substituted alkylene oxides with 2 to 4 carbon atoms in the alkylene radical are used for the polymerization. 
     
     
       8. The process of claim 7 wherein ethylene oxide and/or propylene oxide are used as the alkylene oxides. 
     
     
       9. The process of claim 1 wherein alkali hydroxides are used as the alkaline catalysts.